Background: Dedifferentiated chordomas are rare high-grade malignant spinal tumors for which there is minimal information to help guide treatment.
Objective: To identify prognostic factors associated with increased risk of local recurrence, metastases and reduced survival in a cohort of patients undergoing sacrectomy for 'de novo' dedifferentiated sacral chordoma.
Methods: Review of ten patients undergoing sacrectomy for histologically-confirmed dedifferentiated chordoma at a specialist center. There were six males and four females with a mean age 66.7 years (57-80) and mean follow-up 36.7 months (3-98). Data on prognostic factors were collected.
Results: The commonest presenting symptom was lumbar/gluteal pain. Mean duration of pre-operative symptoms was 3.6 months (2-7). Local recurrence occurred in seven patients and metastases in five. Following sacrectomy, seven died at a mean of 41 months (3-98). Tumor size >10cm in diameter, amount of dedifferentiation within the conventional chordoma, sacroiliac joint infiltration, and inadequate resection margins were associated with increased risk of recurrence and reduced survival. Surgical approach, cephalad extent of primary tumor and adjuvant radiotherapy did not affect oncological outcomes.
Conclusion: Dedifferentiated chordomas are aggressive malignant tumors with a higher risk of local recurrence, metastases and early mortality than conventional chordomas. Tumor diameter >10cm, marginal resection, and sacroiliac joint infiltration may be associated with increased risk of local recurrence and mortality. Those with a smaller burden of dedifferentiated disease (<1cm2) within the primary chordoma have a better prognosis. Patients should be counseled about these risks prior to surgery and have regular follow-up for detection of local recurrence and metastases.
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